Namely a dial for a portable object such as a timepiece made, for example, of a transparent plastic material. A semi-transparent layer is, for example, printed on an upper surface of the dial facing the user's side so as to conceal from the user's view the components, such as a solar cell, disposed under the surface of the dial. A fraction of the upper surface of the dial is left clear of any printing so as to provide a transparent aperture. A digital display device, such as a liquid crystal display cell, is adhesive bonded under the surface of the dial, plumb with the aperture, so that the information displayed by the liquid crystal display device can be read by the user.
The drawback of this type of dial is that it is not possible to give it a particular finish with the aid of conventional mechanical finishing means. Indeed, let us imagine, for example, that it is desired to brush the dial using a metal brush in order to form fine lines in the dial which will radiate out from the centre of the dial. These fine lines, through the phenomenon of light reflection, will give the dial a shimmering and changing appearance. Unfortunately, it is understood that in the case of a dial which has one portion that must remain transparent, it is not possible to perform such a mechanical brushing treatment. Indeed, it is impossible to stop the brushing when the brush passes in proximity to the transparent aperture to prevent the brush scratching the aperture, which would make it difficult to read the information displayed by the digital display device. It is thus clear that in the case of a dial made of transparent material having one portion that must remain transparent, it is not possible to apply mechanical finishing operations to such a dial, which considerably limits the final appearance that can be given to the dial.
Moreover, since the digital display device is directly bonded under the surface of the dial, plumb with the transparent aperture, it is also necessary to provide this aperture with an antireflective layer in order to ensure good readability of the information displayed by the digital display device.